Film centering device

ABSTRACT

A sheet centering device for centering at least first and second sized sheets comprising: a base member having a surface along which a sheet is transported along a sheet transport path; a skew roller mounted on the base member at an angle to the sheet transport path; a first sheet guide mounted on the base member along one side thereof; a second sheet guide mounted on the base member parallel to but inwardly of the first sheet guide; and a drive assembly for moving the second sheet guide between a position out of the sheet transport path when a first sized sheet is transported along the sheet transport path and a position in the sheet transport path when a second sized sheet smaller than the first sized sheet is transported along the sheet transport path.

FIELD OF THE INVENTION

This invention relates in general to sheet handling systems and more particularly to the centering of sheets used in image reproduction apparatus.

BACKGROUND OF THE INVENTION

Image reproduction apparatus, such as electrographic, ink jet and laser printers, use media sheet such as paper or film to produce copies of images such as medical images. Typically, the media sheet needs to be correctly positioned in the apparatus with respect to the printing system. Methods for positioning the media sheet include positioning the media sheet so that one edge of the sheet is positioned against a reference surface located at one end of the printing system and positioning the sheet such that the center of the sheet comes in the center of the printing system. One technique for carrying out the latter method is to provide members on both sides of the sheet transport path to center the sheet in the apparatus. This technique is relatively complex and inefficient. A technique for carrying out the former method is disclosed in U.S. Pat. No. 4,982,946, issued Jan. 8, 1991, inventors Uchimura et al. As disclosed, a skew roller arranged at an angle to the transport direction of a paper sheet positions an edge of the paper sheet against a fixed reference guide running parallel to the transport direction.

There is no disclosure in this patent of applying this technique for different widths of sheet. If different widths of sheet are positioned against the fixed guide, they are edge justified and the centerline of the sheet would not pass through the centerline of the apparatus.

There is thus a need in reproduction apparatus for a simple and efficient technique for centering different size sheets in the apparatus.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a solution to these needs and problems.

According to a feature of the present invention, there is provided a sheet centering device for centering at least first and second sized sheets comprising:

-   -   a base member having a surface along which a sheet is         transported along a sheet transport path;     -   a skew roller mounted on said base member at an angle to said         sheet transport path;     -   a first sheet guide mounted on said base member along one side         thereof;     -   a second sheet guide mounted on said base member parallel to but         inwardly of said first sheet guide; and     -   a drive assembly for moving said second sheet guide between a         position out of said sheet transport path when a first sized         sheet is transported along said sheet transport path and a         position in said sheet transport path when a second sized sheet         smaller than said first sized sheet is transported along said         sheet transport path.

ADVANTAGEOUS EFFECT OF THE INVENTION

The invention has the following advantages.

-   -   1. Different widths of media sheet can be positioned in         reproduction apparatus such that they are transported along the         centerline of the apparatus.     -   2. As opposed to a mechanism that uses guides on both sides of         the sheet to center the sheet, the invention is relatively         simple and reliable.     -   3. The same roller assembly is used to center the sheet and         transport the sheet into the printing system transport rollers.     -   4. The centering of the sheet to a known position is constant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view, elevational view of a reproduction apparatus incorporating the present invention.

FIG. 2 is a top perspective view of an embodiment of the present invention, showing the small sheet guide in a down position.

FIG. 3 is a bottom perspective view of the embodiment shown in FIG. 2.

FIG. 4 is a top perspective view of the embodiment of FIG. 2 showing the small sheet guide in the up position.

FIG. 5 is a bottom perspective view of the embodiment shown in FIG. 4.

FIGS. 6A and 6B are respective side elevational views respectively showing the small sheet guide in the up and down positions.

FIGS. 7A, 7B and 7C are top plan views illustrating how a sheet would be moved when the small sheet guide is in the up position. Similar action would occur for the large sheet but the sheet would move along the large sheet guide instead of the small sheet guide.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, there will be described reproduction apparatus incorporating an embodiment of the present invention. The apparatus described is a medical image printer in which a medical image is reproduced on heat processable film. As shown, apparatus 100 includes a housing 102, film supply and pick up module 104, optics module 106, film processor module 108 and output tray 110. Module 104 receives a cartridge of unexposed film. The cartridge contains machine readable information including size of the film in the form of an optically readable bar code, or magnetic or radio frequency readable media. The read information is used to control the operation of apparatus 100 including the present invention.

A film pick-up device feeds a sheet of unexposed film from module 104 along a sheet transport path 112. The unexposed film is transported along path 112 from film pick up position 114 to transport rollers 116 at position 118, where it enters the sheet centering device 120 of the present invention. Device 120 includes skew roller 122 at position 124 at which the film is positioned by skew roller 122 against a film guide. The centered film is transported to imaging position 126 including rollers 5 and 6 where the film is exposed to a medical image by optics module 106. The film is transported past positions 132, 134 by transport rollers 136, 138 respectively to image processor 108, at position 139. Processor 108 heat processes the exposed film to produce a developed medical image on the film. The film is transported along path 112 out of processor 108 to output tray 110.

Referring now to FIGS. 2-7C there will be described an embodiment of the film centering device of the present invention. As shown, device 120 includes skew roller 122 mounted at an angle to film direction 32 on member 34 by brackets 36, 38. Roller 122 is driven by skew roller drive motor assembly 3. Skew roller 122 could also be driven by a linkage between it and drive assembly 4. Device 120 includes large film guide 2 fixedly mounted on base plate 34 and small film guide 9 mounted on member 34 for movement into and out of the film path. Further shown are pinch rollers 5 forming an imaging nip with roller 6 and driven by drive motor assembly 4. Small film guide 9 is driven between up and down positions by small film guide lift drive motor assembly 7, lift springs 8, drive motor pulley 10, cam 11, and belt 12. The small film guide could also be driven up by a solenoid or other device.

Operation of device 120 in apparatus 100 is as follows:

For a large sheet of film: The sheet is directed towards a fixed guide 2 and the skew roller 1 is rotated via means of a motor assembly 3. The film is pushed towards and into the edge guide 2 and then slides along the edge guide towards the imaging nip 5, 6. As shown in FIGS. 2 and 3 the small film guide is in the down position out of the film path.

For a small sheet of film: The lift motor assembly 7 is engaged which rotates a shaft/cam assembly 11. (FIGS. 6A and 6B) The cams on the shaft are located directly under the small film guide 9 and as they are rotated the small film guide 9 moves up above the base plate 34 pushed by the cams 11. When the skew roller 1 is engaged it now pushes the film along the small guide edge 9 into the imaging nip 5, 6. FIGS. 4 and 5 show the small film guide in the up position in the film path and FIGS. 7A-7C show film 200 as it moves through device 120 to imaging nip rollers 5.

After imaging a small film sheet, the device can either be left in position or lowered back into it's home position to allow a large film sheet to be imaged. To lower the small film guide 9 back below the base plate, the lift motor assembly 7 is engaged which rotates a shaft/cam assembly 11. The cams on the shaft are located directly under the small film guide 9 and as they are rotated the small film guide 9 is pushed below the base plate by the springs 8 as the cam assembly 11 retreats. (FIGS. 6A, 6B).

The machine would know what size film sheet is loaded by reading the information on the film cartridge after it is inserted into the machine. It would then correctly position the small edge guide into the up or down position.

Because centering of the film to a known position is constant, a smaller border region on the film print as allowed. Furthermore, the offset can be measured during manufacturing and an offset can be added to the machine electronics to allow no border if desired.

Although a fixed large film guide has been described, it will be understood that a large film guide which is movable into and out of the film path may also be provided. Furthermore, more than two film sizes can be accommodated with the addition of other film guides movable into and out of the film path.

Another embodiment of this device would be to have the skew roller assembly 122 rotate. That is, the drive angle of the roller in regards to the sheet could also be varied as different width sheets are passed through the system. The angle setting would be dependent on what size cartridge is loaded in device 104. Similarly it reads the information off of the cartridge. The advantage of this would be a smoother rotation of the sheet and push into the nip rollers.

The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Parts List

-   1 skew roller -   2 large film guide -   3 skew roller drive motor -   4 drive motor assembly -   5,6 rollers -   7 lift drive motor assembly -   8 lift springs -   9 small film guide -   10 drive motor pulley -   11 cam -   12 belt -   32 film direction -   34 base plate -   36,38 brackets -   100 apparatus -   102 housing -   104 module -   106 optics module -   108 film processor module -   110 output tray -   112 sheet transport path -   114 film up position -   116 transport rollers -   118 position -   120 sheet centering device -   122 skew roller -   124 position -   1226 imaging position -   132,134 positions -   136,138 transport rollers -   139 position -   200 film 

1. A sheet centering device for centering at least first and second sized sheets comprising: a base member having a surface along which a sheet is transported along a sheet transport path; a skew roller mounted on said base member at an angle to said sheet transport path; a first sheet guide mounted on said base member along one side thereof, a second sheet guide mounted on said base member parallel to but inwardly of said first sheet guide; and a drive assembly for moving said second sheet guide between a position out of said sheet transport path when a first sized sheet is transported along said sheet transport path and a position in said sheet transport path when a second sized sheet smaller than said first sized sheet is transported along said sheet transport path.
 2. The sheet centering device of claim 1 wherein said first sheet guide is fixedly mounted on said base member.
 3. The sheet centering device of claim 1 wherein said first sheet guide is mounted on said base member for movement between an up position in said sheet transport path and a down position out of said sheet transport path.
 4. The sheet centering device of claim 1 wherein said drive assembly includes a rotatable cam contacting said second sheet guide for moving said guide between said first and second positions.
 5. The sheet centering device of claim 4 wherein said drive assembly includes a lift spring engaging said second sheet guide for biasing said guide against said cam.
 6. The sheet centering device of claim 1 including imaging nip rollers mounted on said base plate and a skew roller drive for rotating said skew roller so as to move a sheet into contact with on of said guides and along said sheet transport path to said imaging nip rollers.
 7. The sheet centering device of claim 1 including means for mounting said skew roller for rotation about an axis perpendicular to said sheet transport path so as to vary the drive angle of said roller in relation to different sized sheets transported along said path. 